In semiconductor technologies, backside-illuminated sensors are used for sensing a volume of exposed light projected towards the backside surface of a substrate. The backside-illuminated sensors can be formed on the front side of the substrate and light projected towards the backside of the substrate can reach the sensors. However, light targeted for one sensor pixel may also have a portion of the light directed toward other pixels, which causes crosstalk among various sensor pixels. Improvements in backside illuminated sensors and/or the corresponding substrate are desired.